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One-step hydrothermal synthesis of silver-doped carbon quantum dots for highly selective detection of uric acid
摘要： In this paper, a simple and convenient fluorescence method for detection of uric acid (UA) based on Ag-doped carbon quantum dots (Ag-CQDs) is developed. The Ag-CQDs contain Ag species could bond with UA, which promoted the electron and/or energy transfer and produced high quenching extent. Thus, the fluorescence intensity of Ag-CQDs decreased in the presence of UA. Under the optimal condition, the UA sensor exhibited a linear response in the range of 0.005-100 μM with a detection limit of 0.35 nM (S/N=3). Ag-CQDs demonstrated high sensitivity and rapid response to UA over a wide range of concentration indicating their great potential as a fluorescent probe for chemical sensing. Moreover, this method has successfully applied to detect UA in human urine samples.
关键词： silver,doping,carbon quantum dots,uric acid,fluorescence
更新于2025-09-11 14:15:04
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Additive Engineering for Efficient and Stable Perovskite Solar Cells
摘要： Perovskite solar cells (PSCs) have reached a certified 25.2% efficiency in 2019 due to their high absorption coefficient, high carrier mobility, long diffusion length, and tunable direct bandgap. However, due to the nature of solution processing and rapid crystal growth of perovskite thin films, a variety of defects can form as a result of the precursor compositions and processing conditions. The use of additives can affect perovskite crystallization and film formation, defect passivation in the bulk and/or at the surface, as well as influence the interface tuning of structure and energetics. Here, recent progress in additive engineering during perovskite film formation is discussed according to the following common categories: Lewis acid (e.g., metal cations, fullerene derivatives), Lewis base based on the donor type (e.g., O-donor, S-donor, and N-donor), ammonium salts, low-dimensional perovskites, and ionic liquid. Various additive-assisted strategies for interface optimization are then summarized; additives include modifiers to improve electron- and hole-transport layers as well as those to modify perovskite surface properties. Finally, an outlook is provided on research trends with respect to additive engineering in PSC development.
关键词： perovskite solar cells,additives,stability,Lewis acid,defect passivation
更新于2025-09-11 14:15:04
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Detection of theophylline using molecularly imprinted polymers based on thioglycolic acid-modified CdTe quantum dots
摘要： Molecularly imprinted polymers (MIPs) and quantum dots (QDs) have been widely employed to fabricate highly sensitive and selective sensor. Here, we developed a fluorescence nanosensor based on thioglycolic acid-modified CdTe QDs that is coated with molecularly imprinted polymers for the specific detection of theophylline (THP). Initially, water-soluble thioglycolic acid-modified CdTe QDs were synthesized by refluxing method. Then, MIPs-coated QDs (MIPs-QDs) composite was produced by sol–gel process using THP as a template. Therefore, the selectivity of the molecular imprinting technique and advantages of QDs were combined. The prepared QDs and the MIPs-QDs were characterized using X-ray diffraction technique, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and fluorescence spectrometry. Finally, this sensing system was successfully used to detect THP in human plasma samples with recoveries of 90% to 108%. A very good linear relationship was observed between the decreasing in the fluorescence intensity of MIPs-QDs and increasing the THP concentration within concentration range of 0.14–3.05 μmol L?1, with a correlation coefficient of 0.9992 and detection limit of 0.07 μmol L?1.
关键词： Molecularly imprinted polymers,Thioglycolic acid-modified CdTe QDs,Theophylline
更新于2025-09-11 14:15:04
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A Facile One Step Hydrothermal Synthesis of Carbon Quantum Dots For Label -Free Fluorescence Sensing Approach to Detect Picric Acid in Aqueous Solution
摘要： In this work, a facile one step approach has been applied for the synthesis of nitrogen and sulphur co-doped water soluble carbon quantum dots (NS-CQDs) through hydrothermal treatment of L-Lysine and thiourea. The obtained NS-CQDs have a high quantum yield (QY) of 53.19 % and emit strong blue fluorescence under UV light excitation of wavelength 365 nm. The morphology of NS-CQDs is spherical in shape and their sizes are distributed in the range 5-8 nm with average diameter 6.86 nm. Moreover the NS-CQDs show excitation dependent emission behavior due to quantum confinement effect. Additionally, NS-CQDs serve as a fluorescent probe for the selective and sensitive detection of picric acid (PA) in aqueous solution. A good linear response to PA in the concentration range 1-10 μM with a detection limit 0.24 μM has been obtained. The high selectivity of PA by NS-CQDs is suggested to be arises from fluorescence resonance energy transfer (FRET) mechanism. Finally these NS-CQDs fluorescent probes have been examined in real water sample by measuring the concentration of PA in tap water.
关键词： Fluorescence,quantum yield,Picric acid,Carbon quantum dots
更新于2025-09-11 14:15:04
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Copper indium sulphide:zinc sulphide (CIS:ZnS)-alloyed quantum dots as an eco-friendly absorber in solar cells
摘要： Synthesis and characterization of less toxic copper indium zinc sulphide (CIS:ZnS)-alloyed quantum dots (QDs) were carried out and the ligand exchange process towards the ef?ciency enhancement in CIS:ZnS QD-sensitized solar cell was demonstrated. The colloidal CIS:ZnS QDs were synthesized by an inexpensive heat up method with oleic acid as the capping ligand. The optical properties were analysed through ultraviolet–visible absorption and photoluminescence emission spectroscopy. The in?uence of the ligand exchange process on the CIS:ZnS QD-based solar cells was analysed with the fabrication of two batches of solar cells. The ligand exchange process was con?rmed from Fourier transform infrared and thermogravimetric analyses. The QD-sensitized solar cells were fabricated using a CIS:ZnS QD-loaded titania photoanode and by employing copper sulphide as the counter electrode. The photovoltaic performance of the fabricated QD solar cells was analysed through photovoltaic characterization methods (current density–voltage characteristics of the devices under the simulated solar light conditions and external quantum ef?ciency measurements). The ligand-exchanged QD-loaded solar cells show enhanced power conversion ef?ciency compared to the long chain ligand-capped CIS:ZnS QD-sensitized solar cells.
关键词： Copper indium zinc sulphide,less hazardous QDs,ligand exchange,oleic acid,ef?ciency enhancement,QD-sensitized solar cells
更新于2025-09-11 14:15:04
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Synthesis of magnetically reusable Fe3O4/TiO2-N, P co-doped graphene quantum dot nancomposites using hexachlorocyclophosphazene; high photoluminance property and photocatalytic promoter
摘要： Hexachlorocyclophosphazene (PNT) was used as new P and N doping source for synthesizing of graphene quantum dots (N,P-GQDs). Hydrothermal process was applied for importing P and N atoms into the GQDs texture. Three different amounts of hexachlorocyclophosphazene were used to obtain optimum sample. All products were characterized using XRD, SEM, PL, FT-IR, EDS, AFM, TEM and Raman spectroscopy. XRD result indicated that the sample with 0.1 g of PNT (sample 2) has sharp peaks with medium wide and intensity and has a more principle in structure in comparison with other samples. So sample 2 was chosen as optimum sample. Also sample 2 showed strongest PL emission under excitation at 396 nm which was an evidence of successful doping of P and N atoms in the GQDs structure during hydrothermal process. The Fe3O4/TiO2/N,P-GQDs nanocomposite which was obtained using S2 as N,P-GQDs source showed a high activity in organic dye degradation. The higher catalytic activity of Fe3O4/TiO2/N,P-GQDs versus TiO2 can be attributed to the synergistic effect between TiO2 and N,P-GQDs. The magnetic properties of the catalysts allow fast separation of the catalysts from the reaction media.
关键词： Hexachlorocyclophosphazene,Fe3O4/TiO2/N,GQDs,Citric acid,P-GQDs nanocomposite,Photoluminescence
更新于2025-09-11 14:15:04
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Comparison of spectral and thermal properties and antibacterial activity of new binary and ternary complexes of Sm(III), Eu(III) and Gd(III) ions with N-phenylanthranilic acid and 1,10-phenanthroline
摘要： New binuclear binary and ternary complexes of Sm(III), Eu(III), and Gd(III) ions with N-phenylanthranilic acid and 1,10-phenanthroline were obtained in solid phase and characterized by chemical and elemental analysis, molar conductance, UV–VIS and IR spectroscopies as well as thermoanalytical techniques (TG/DTG–DSC coupled with MS and FT-IR). The dilution method was used to examine the antibacterial activity of the synthesized compounds. The spectroscopic studies indicated that the carboxylate group of N-phenylantranilate ligand is involved in the coordination of metal ion, both in binary and ternary complexes. Thermal decomposition of the obtained compounds was carried out in air and nitrogen atmosphere. During heating, the complexes decompose via intermediate products to the oxide (Ln2O3) in air atmosphere and to the oxide (Ln2O3) or oxide polluted by carbon (Ln2O3+nC) in nitrogen atmosphere. The dehydration process was discussed in relation to the nature of water present in these compounds. Using coupled TG–FTIR–MS techniques the decomposition pathways of the synthesized compounds were examined. Additionally, gaseous products released during pyrolysis and thermal oxidation of the complexes were identified. All the complexes exhibit marked activity against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and one Gram-positive (Staphylococcus aureus) bacterial strains. The ternary complexes, especially Gd(III) complex in comparison with the binary ones, have enhanced activity against Escherichia coli. Moreover, antibacterial activity of the synthesized compounds with respect to Pseudomonas aeruginosa is comparable to tetracycline and greater than for kanamycin, erythromycin, and ampicillin.
关键词： 1,10-phenanthroline,Thermal analysis,Lanthanide complexes,N-phenylanthranilic acid,EGA
更新于2025-09-11 14:15:04
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Effects of Water Matrices on the Degradation of Naproxen by Reactive Radicals in the UV/Peracetic Acid Process
摘要： The UV/peracetic acid (UV/PAA) process as a novel advanced oxidation process has been reported to produce carbon-centered radicals (R-C?) for Naproxen (NAP) degradation, which is a representative of naphthyl structure substances. Real water matrices, such as carbonate and bicarbonate ions (CO3 2-/HCO3 -), humic acid (HA), and chloride ion (Cl-), may react with these reactive radicals and change their contributions to NAP degradation. The results showed that R-C? contributed 60.8% and ?OH contributed 39.2% to NAP degradation in pure water by a competition method. CO3 2-/HCO3 - (0–20 mM) showed minimal effect on NAP degradation in the UV/PAA process, meanwhile, it has observable inhibition effect on NAP degradation in the UV/H2O2 process (mainly of ?OH) and minimal effect in the UV/PAA process with tert-butanol (TBA) (mainly of R-C?). Results suggested that CO3 2-/HCO3 - could react with ?OH yielding CO3?- with low reactivity to NAP, CO3?- could further react with PAA to produce R-C?. This speculation was confirmed by the increased contribution of R-C? to NAP degradation with the increase of CO3 2-/HCO3 - concentration through the competition method. HA (0–5 mg/L) had a higher scavenging capacity for R-C? than ?OH because HA with naphthyl structure was likely to be attacked by R-C?. Cl- (0–200 mM) had little effect on NAP degradation in the UV/PAA and UV/H2O2 processes, while exerted an observable inhibition on NAP degradation in the UV/PAA process with TBA. This finding suggested that Cl- could react with R-C? to produce Cl?, which could further convert into HOCl?-, and then excess ?OH was formed. The new knowledge on the conversion of reactive radicals obtained in this study provides an important basis for facilitating further research on the UV/PAA advanced oxidation.
关键词： Real Water Matrices,UV/Peracetic Acid Process,Naproxen,Reactive Radicals
更新于2025-09-11 14:15:04
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Parallels and Interrelated Regularities in the Change of the Bulk and Surface Properties of CdBVI–CdTe Systems
摘要： Comprehensive studies of the volume (structural, optical, electrophysical) and surface (acid-base, adsorption) properties of solid solutions and binary components of the CdS–CdTe and CdSe–CdTe systems are carried out. The regularities in the changes of these properties with a variation in the composition and the parallels between the patterns within each system and under their comparison are established. The leading influence of the common binary component, cadmium telluride, on the properties of solid solutions of both systems is revealed. The possibility of predicting the surface activity of these new materials with respect to gases of different electronic natures is shown on the basis of the results of less labor-intensive studies of the bulk physical and chemical properties (in comparison with direct studies of the surface characteristics, i.e., acid-base and adsorption characteristics). Practical recommendations on using the obtained materials in corresponding sensors are made.
关键词： acid-base,adsorption properties,sensors,solid solutions,chalcogenides,new materials,electrophysical,structural,optical
更新于2025-09-11 14:15:04
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Microwave assisted sol–gel synthesis of titanium dioxide using hydrochloric and acetic acid as catalysts
摘要： Titanium dioxide (TiO2) was synthesized by microwave assisted sol–gel. The effect of the acid type used as catalyst on the phase transformation of TiO2 was investigated (hydrochloric or acetic acid). The samples obtained were characterized by scanning electron microscopy (SEM), this micrographs showed particles with irregular shapes. The results of Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed present signals of O and Ti. When hydrochloric acid was used as catalyst, three titania polymorphs were detected by X-ray diffraction (XRD), anatase, rutile and brookite, where the crystallite size was in the range of 9 and 16 nm. On the other hand, a single anatase phase was formed when acetic acid was used after only 15 min of reaction time. The anatase average crystallite size was obtained between 11 and 22 nm.
关键词： Microwave-assisted sol–gel,Acetic acid,Hydrochloric acid,Titanium dioxide
更新于2025-09-10 09:29:36